The primary method of detection of certain pathogenic infections within a bodily sample (e.g., a blood sample) is the microscopic examination of the bodily sample, and visual confirmation of the presence and concentration of the pathogen. Staining a bodily sample with a stain or dye prior to microscopic examination is often used to enhance contrast in the microscopic image, and to visually highlight cells having a particular biological makeup. In particular, some fluorescent dyes have an affinity for nucleic acid in cells. When excited by fluorescent light at an appropriate wavelength, the nucleic acid will fluoresce. Accordingly, fluorescent dyes are sometimes used to differentially stain parts of a cell for detection under a microscope. For example, when excited by blue light, the fluorochrome Acridine Orange bound to DNA will emit green light, and when bound to RNA will emit red light. Blood pathogens such as Anaplasma marginale, Hemobartonella, trypanosomes, Plasmodium spp., Babesia spp. and others have all been detected with Acridine Orange.
While the primary method of detecting pathogens remains visual identification in a microscopic bright field image, fluorescent microscopy has been used as well, though to a lesser extent. However, in both cases, detection of a pathogenic infection by manual identification of pathogens suffers from two main drawbacks: many settings (especially rural) are not equipped to perform the test, and the accuracy of the results depends on both the skill of the person examining the sample and the levels of the pathogen in the sample. Accordingly, attempts have been made to automate the detection of pathogens in a bodily sample.